Sharks and rays are increasingly being identified as threatened with extinction, prompting urgent assessments of their local or regional populations. We need accurate information on population size, structure and connectivity to understand the conservation requirements of a species, develop appropriate management strategies and monitor population health over time.
Conservation genetics combine many different scientific disciplines, such as evolutionary biology, ecology and genetics, and allow us to examine movement patterns, relatedness of individuals or heredity of certain traits.
For instance, manta rays which have a very distinctive body coloration including natural spot patterns on their ventral surface, can have two variant ‘color morphs’ – the melanistic (black) or rarer leucistic (white) morph.
A PhD study is currently underway using DNA analysis to estimate effective population size, investigate spatial connectivity and generational relatedness of two focal populations in Indonesia and Southern Mozambique. This study will deepen our knowledge of the structure of reef manta ray populations and guide management decisions in the future.
For whale sharks, the global whale shark population has been split into two distinct ‘subpopulations’ in the Atlantic and Indo-Pacific respectively based on the results of genetic studies, tagging and photo identification work. However, we think it is likely that fine-scale population structure also exists across such broad areas and are investigating this in locations such as Mozambique, Tanzania, Qatar, Mexico and Ecuador. The focus of our research is on the reproductive ecology and cryptic life-stages of this endangered species.
Population structures and patterns of whale sharks and manta rays will help us identify movement patterns and may highlight key habitats such as breeding or pupping grounds, allowing us to create conservation strategies to safeguard regionally declining populations.